Plastic bags containing an integral zipper or fastener with opposing male and female elements, such as illustrated by U.S. Pat. No. Re. 28,969, have been on the market place for a number of years. While bags with the integral zipper have many advantageous features, one of their difficulties has been in aligning and pressing together the zipper elements for closing of the bags by the average consumer. For this reason, attempts have been made to add closing devices or tools to the bags to permit ready closing of the zipper. Illustrations of such devices are shown in U.S. Pat. Nos. 3,122,807; 3,360,875; 3,790,992 and 3,806,998, for example. However these devices have not been particularly economical, not normally reusable, nor very successful in the market place. The need for an economical, reusable closing device which merely acts as a simple extension of the thumb and finger remained until the present invention was achieved.